The conventional semiconductor production systems have mainly been the few-kinds mass-production systems represented by the production of memories such as DRAMs. The scale is such that several ten thousands of substrates can be processed per month with a large-scale investment of several hundred billion yen. However, it is strongly desired to establish a staged investment type small-scale semiconductor production system that can make sufficient profits even with those products, such as system LSIs for information home appliances, that are very small in lifetime production amount. The situation is such that since current semiconductor manufacturing apparatuses are monofunctional, an increase in the number of apparatuses and an increase in the investment amount are inevitably brought about and thus small-scale lines cannot be constructed at all. The situation is such that it is difficult to realize small-scale production lines unless a plurality of processes are carried out by a single substrate processing apparatus.
Cases are increasing in which, in order to carry out a uniform CVD process in the plane of a 300 mmφ or meter-square large-size substrate, a shower head having gas ejection holes is disposed just above the substrate in a process chamber, thereby facilitating uniform diffusion of a gas onto the surface of the substrate. Further, by forming the shower head out of a metal material, it also becomes possible to perform RIE by generating a self-bias on the side of the processing substrate using the shower head itself as a ground surface. By disposing such a metal shower head, it becomes possible to fabricate an apparatus that can perform a plurality of processes in a single process chamber.
When different processes are performed by switching the kind of gas one after another in the same substrate processing chamber, materials forming the inside of the chamber including a gas-supply shower head become one of the important factors. Since the processes such as CVD, RIE, oxidation, and nitriding are performed in the single substrate processing chamber, a cleaning process for resetting the chamber to the initial state per process becomes very important. A fluorine-based gas is mainly used as a cleaning gas in both plasma cleaning and plasmaless cleaning and, in this event, it is preferable in terms of production that the cleaning be carried out while maintaining a process temperature of 250 to 500° C. in the process chamber, the exhaust system, and so on. However, occurrence of corrosion of the forming metal materials cannot be avoided at such a temperature and thus leads to a cause of metal contamination on the surface of a processing substrate. Further, since not only a fluorine-based gas but also a chlorine-based gas are used as etching gases in RIE for processing metal materials, a surface treatment of a metal material such as an Al alloy or stainless of an RIE apparatus is essential. For example, in the case of the Al alloy, an alumite treatment in which anodic oxidation is performed using an acid-based anodization solution to thereby form a porous thick aluminum oxide coating film of several tens of μm has conventionally been a general technique. However, this alumite coating film has a very large effective surface area because of its porous structure and thus there have been problems of the occurrence of contamination during the process due to generation of large quantities of water and organic outgas, and of the prolongation of a downtime such that the degree of vacuum cannot readily increase upon starting a vacuum apparatus after maintenance.